Linear actuator driven molecular sieve oxygen generator

Abstract

An apparatus for generating high purity oxygen is described which comprises a linear actuator, a dual acting air cylinder, two molecular sieve beds, and valving. The linear actuator drives the air cylinder back and forth, compressing air on both the forward and return stroke. On each stroke, fresh air is compressed into one of the beds, generating oxygen. Simultaneously, the opposite bed exhausts to ambient pressure and the non-compressing side of the cylinder draws in fresh air. The cylinder then reverses, which compresses air into the opposing bed and allows the first bed to exhaust.

We claim:  
     
       1. An apparatus for producing oxygen, comprising: 
       (a) a dual acting air cylinder having a piston member comprising an axial piston rod coupled to a piston slidably mounted in said cylinder;  
       (b) an actuator coupled to said rod for retracting and extending said piston in said cylinders thereby alternately compressing air on a piston side and a rod side of said cylinder;  
       (c) first and second beds containing molecular sieve coupled to said cylinder; and  
       (d) valving coupled to said cylinder and to said first and second beds, said valving being operable in recurring cycles in which said piston member is retracted and extended;  
       so that in each first half cycle of operation in which said piston is being retracted, ambient air flows into said rod side of said cylinder, pressurized air is simultaneously directed from said piston side of said cylinder to said first bed to adsorb nitrogen and provide a flow of oxygen gas from said first bed, and said second bed is simultaneously depressurized and previously adsorbed nitrogen gas is desorbed and exhausted from said second bed;  
       and in each second half cycle of operation in which said piston is being extended, ambient air flows into said piston side of said cylinder, pressurized air is simultaneously directed from said rod side of said cylinder to said second bed to adsorb nitrogen and provide a flow of oxygen gas from said second bed, and said first bed is simultaneously depressurized and previously adsorbed nitrogen gas is desorbed and exhausted from said first bed;  
       whereby by cyclically repeating said operation in which said piston member is retracted and extended, a continuous stream of oxygen is produced.  
     
     
       2. An apparatus as set forth in claim  1  wherein said valving comprises a first set of valves coupled between said cylinder and said first and second beds to control air flow to and from said cylinder and nitrogen exhaust flow from said first and second beds and a second set of valves coupled to said first and second beds to control oxygen flow from said first and second beds. 
     
     
       3. An apparatus as set forth in claim  2  wherein said first set of valves comprises first and second four way valves, said first four way valve being operable to permit only the flow of compressed air from said piston side of said cylinder to said first bed during each said first half cycle of operation and to permit only the flow of ambient air to said rod side of said cylinder and the exhaustion of nitrogen gas from said second bed during each said second half cycle of operation, and said second four way valve being operable to permit only the flow of ambient air to said piston side of said cylinder and the exhaustion of nitrogen gas from said first bed during each said first half cycle of operation and to permit only the flow of compressed air from said rod side of said cylinder to said second bed during each said second half cycle of operation. 
     
     
       4. An apparatus as set forth in claim  2  wherein said second set of valves comprises first and second two way valves, said first two way valve being operable to permit the flow of oxygen gas from said first bed only during each said first half cycle of operation and said second two way valve being operable to permit the flow of oxygen gas from said second bed only during each second half cycle of operation. 
     
     
       5. An apparatus as set forth in claim  1  further comprising purge means for regeneration of said first and second beds during depressurization of said first and second beds.